The U.S. government viewed involvement in the war as a way to prevent a communist takeover of South Vietnam as part of their wider strategy of containment. The North Vietnamese government and Viet Cong viewed the conflict as a colonial war, fought initially against France, backed by the U.S., and later against South Vietnam, which it regarded as a U.S. puppet state. American military advisors arrived in what was then French Indochina beginning in 1950. U.S. involvement escalated in the early 1960s, with troop levels tripling in 1961 and tripling again in 1962. U.S. combat units were deployed beginning in 1965. Operations spanned international borders, with Laos and Cambodia heavily bombed. American involvement in the war peaked in 1968, at the time of the Tet Offensive. After this, U.S. ground forces were gradually withdrawn as part of a policy known as Vietnamization. Despite the Paris Peace Accords, signed by all parties in January 1973, fighting continued.
U.S. military involvement ended on 15 August 1973 as a result of the Case--Church Amendment passed by the U.S. Congress. The capture of Saigon by the Vietnam People's Army in April 1975 marked the end of the war, and North and South Vietnam were reunified the following year. The war exacted a huge human cost in terms of fatalities (see Vietnam War casualties). Estimates of the number of Vietnamese soldiers and civilians killed vary from fewer than one million to more than three million. Some 200,000--300,000 Cambodians, 20,000--200,000 Laotians and 58,220 U.S. service members also died in the conflict.